Afther I did the DS II Swap...the A/C/Vents are NOT working...where does the vac hose that go from the A/C Control Panel through the firewall go??

There are two hoses coming out of the firewall. One (Black) is vacuum going IN to the AC control switch, the other (Black/White) is vacuum coming OUT connected to the vacuum (recirculate air) valve on the heater box (just above the blower motor).

The vacuum line coming off the intake manifold must have a check valve in it, otherwise the vent position would change to (default) defrost every time you went WOT. All of the setups I've seen use a can or ball shaped vacuum tank too. Maybe there are some factory setups with this tank.

Last edited by CountryBumkin; 08-02-2014 at 10:36 AM.
Reason: spelling

There are two hoses coming out of the firewall. One (Black) is vacuum going IN to the AC control switch, the other (Black/White) is vacuum coming OUT connected to the vacuum (recirculate air) valve on the heater box (just above the blower motor).

The vacuum line coming off the intake manifold must have a check valve in it, otherwise the vent position would change to (default) defrost every time you went WOT. All of the setups I've seen use a can or ball spaced vacuum tank too. Maybe there are some factory setups with this tank.

Spot on! Best description I've seen of the system in a while.

FWIW, I repped ya for it. Finally found someone I could actually rep......

Well, like I said the a/c and vents worked before the DS II swap. I only see a black hose coming through the firewall under the heater box (its not connected to anything)...it cam unhooked from wherever...does anyone have a diagram...do I need to add something because I removed the computer??

Well, like I said the a/c and vents worked before the DS II swap. I only see a black hose coming through the firewall under the heater box (its not connected to anything)...it cam unhooked from wherever...does anyone have a diagram...do I need to add something because I removed the computer??

If that hose is not hooked to anything, then somewhere you also have a vacuum port or line that is open. Find it, and make two meet.

No need to add anything, unless you took out the softball sized vac canister that is supposed to help run the HVAC system. In that case, you need to add it back.......

I did the swap a few months ago...so I did have to plug a bunch pf vac ports on the vac tree near the carb. I guess I'll have to see which one it fits. I'm not sure where the canister is (I didnt remove it for sure). I'm familar w/ the juice can size one...I dont have that.

Here you go. Hope this helps. Note that the vacuum comes from (page 92) the "vacuum distribution block" this is a three port tee (usually mounted to the firewall near the evaporator housing). The center port goes to the intake manifold (where the power brake booster connector is located), the left port goes to the A/C heater "R" (page 82) in the diagram below, and the right port goes to the automatic transmission module. If this manifold block/tee broke somewhere in the past the previous owner probably recreated it with some fittings, etc. so it may not be on the firewall anymore. The bottom line is that you need manifold vacuum to "R" and a check valve in that hose.

That's better!! I still don't see where 2 different lines are connected (or should be connected). Again, I only have one black line coming through the firewall. I just wanted to get a jump on working on this later today or tomorrow.